Increased skin pH a risk factor for atopic dermatitis

Acidity of the skin appears to be significantly higher in atopic dermatitis (AD) patients than in controls without the condition, indicating that increased skin pH may heighten the risk of developing AD, according to a study.

Skin pH protects against outside microorganism and bacteria colonization, as well as helps adhesion of nonpathogen bacteria on skin, said lead investigator Dr Ratih Vibriyanti Karna from the Udayana University in Bali, Indonesia. Acidity plays an important role in maintaining skin barrier permeability and homeostasis, as well as stratum corneum desquamation and integrity/cohesion.

In the study, the investigators measured the skin pH of 31 paediatric and adult AD patients (54.8 percent female; 74.2 percent had mild-to-moderate disease) and compared it with those of matched controls (n=31).

The mean pH value in the AD group was significantly higher than in the control group (6.25 vs 5.20; p<0.05). Analysis revealed that compared with a low pH (<5.20), a high pH (>5.20) was strongly associated with a greater likelihood of developing AD (odds ratio, 41.5; 95 percent CI, 5.00–344.76; p=0.000). [Karna RV, et al, Regional Conference of Dermatology 2018]

“One of the most important factor in AD pathogenesis is pH value,” Karna said.

Among patients, increased skin pH is associated with decreased sebum secretion, reduced lipid maturation in the stratum corneum and filaggrin degradation, the investigator noted. These factors, along with poor hydration, all contribute to xerosis or dry skin.

The goals of AD therapy include improving the skin’s barrier function, suppressing inflammation and relieving pruritus. According to Karna, a good epidermal barrier will improve overall skin condition and maintain skin physiology, such as hydration and pH.

As such, AD patients may benefit from maintaining an optimal skin pH by using soaps that help balance acidity and emollients to improve skin barriers, the investigator added.

Published data regarding the pH of currently available cleansers and emollients have to be updated, as pointed out in a review. Additionally, the utility of pH in these products should be explored in well-designed studies comparing those of varying pH, and quantifying both the immediate effects and the long-term clinical benefit of sustained use in AD patients. This is important as the consideration of pH normalization will continue to be part of a comprehensive treatment plan in AD and other cutaneous diseases. [J Clin Med 2015;4:970-978]